This invention relates to a rotary seal assembly which provides a dynamic seal with respect to a rotating shaft such as a crankshaft. More particularly, it relates to a lip seal assembly which is adjustable axially along such shaft.
Rotary seals, such as those used on the ends of crankshafts, often fail prematurely due to the rubbing action which occurs between the seal face and the running surface of the shaft at the line of contact. This rubbing action causes the wearing off of the seal face as well as the wearing of a groove into the shaft. Consequently, sealing effectiveness is considerably reduced. This problem is particularly severe when the shaft and seal are exposed to an environment having abrasive particles which tends to increase the wear rate. This leads to frequent replacement of the seal.
In addition, after sufficient wear has occurred to cause leakage past the seal, the crankshaft is normally removed from the engine and the shaft running surface reground in order to eliminate the groove worn therein by the seal. The crankshaft is then subsequently reassembled with a new seal.
U.S. Pat. No. 3,595,585 proposes a method for overcoming this problem. The subject patent describes the utilization of a rotary seal assembly which is removed from the shaft and axially reversed and remounted, such that the seal face is repositioned in a new location on the running surface of the shaft. However, problems exist with this method in that only a single additional wear location is thus provided. Another proposal is that found in U.S. Pat. No. 3,866,813, assigned to the assignee hereof. In that patent, an adapter and retainer are threadably coupled such that selective rotation of one with respect to the other permits the axial location of the retainer carrying a lip seal to be changed. While this does provide for a large number of positions along the shaft surface structure, it is relatively complex and costly.